The Use of Electroencephalography as an Informative Tool in Assisting Early Clinical Management after Sport-Related Concussion: a Systematic Review

Prefrontal Cortex Activity During Gait in People With Persistent Symptoms After Concussion

BACKGROUND

Concussions result in transient symptoms stemming from a cortical metabolic energy crisis. Though this metabolic energy crisis typically resolves in a month, symptoms can persist for years. The symptomatic period is associated with gait dysfunction, the cortical underpinnings of which are poorly understood. Quantifying prefrontal cortex (PFC) activity during gait may provide insight into post-concussion gait dysfunction. The purpose of this study was to explore the effects of persisting concussion symptoms on PFC activity during gait. We hypothesized that adults with persisting concussion symptoms would have greater PFC activity during gait than controls. Within the concussed group, we hypothesized that worse symptoms would relate to increased PFC activity during gait, and that increased PFC activity would relate to worse gait characteristics.

METHODS

The Neurobehavior Symptom Inventory (NSI) characterized concussion symptoms. Functional near-infrared spectroscopy quantified PFC activity (relative concentration changes of oxygenated hemoglobin [HbO2]) in 14 people with a concussion and 25 controls. Gait was assessed using six inertial sensors in the concussion group.

RESULTS

Average NSI total score was 26.4 (13.2). HbO2 was significantly higher (P = .007) for the concussed group (0.058 [0.108]) compared to the control group (-0.016 [0.057]). Within the concussion group, HbO2 correlated with NSI total symptom score (ρ = .62; P = .02), sagittal range of motion (r = .79; P = .001), and stride time variability (r = -.54; P = .046).

CONCLUSION

These data suggest PFC activity relates to symptom severity and some gait characteristics in people with persistent concussion symptoms. Identifying the neurophysiological underpinnings to gait deficits post-concussion expands our knowledge of motor behavior deficits in people with persistent concussion symptoms.

Adolescent Sport-Related Concussion and the Associated Neurophysiological Changes: A Systematic Review

BACKGROUND

Sport-related concussion (SRC) has been shown to induce cerebral neurophysiological deficits, quantifiable with electroencephalography (EEG). As the adolescent brain is undergoing rapid neurodevelopment, it is fundamental to understand both the short- and long-term ramifications SRC may have on neuronal functioning. The current systematic review sought to amalgamate the literature regarding both acute/subacute (≤28 days) and chronic (>28 days) effects of SRC in adolescents via EEG and the diagnostic accuracy of this tool.

METHODS

The review was registered within the Prospero database (CRD42021275256). Search strategies were created and input into the PubMed database, where three authors completed all screening. Risk of bias assessments were completed using the Scottish Intercollegiate Guideline Network and Methodological Index for Non-Randomized Studies.

RESULTS

A total of 128 articles were identified; however, only seven satisfied all inclusion criteria. The studies ranged from 2012 to 2021 and included sample sizes of 21 to 81 participants, albeit only ∼14% of the included athletes were females. The studies displayed low-to-high levels of bias due to the small sample sizes and preliminary nature of most investigations. Although heterogeneous methods, tasks, and analytical techniques were used, 86% of the studies found differences compared with control athletes, in both the symptomatic and asymptomatic phases of SRC. One study used raw EEG data as a diagnostic indicator demonstrating promise; however, more research and standardization are a necessity.

CONCLUSIONS

Collectively, the findings highlight the utility of EEG in assessing adolescent SRC; however, future studies should consider important covariates including biological sex, maturation status, and development.

Overview of methods and available tools used in complex brain disorders

Complex brain disorders, including Alzheimer's dementia, sleep disorders, and epilepsy, are chronic conditions that have high prevalence individually and in combination, increasing mortality risk, and contributing to the socioeconomic burden of patients, their families and, their communities at large. Although some literature reviews have been conducted mentioning the available methods and tools used for supporting the diagnosis of complex brain disorders and processing different files, there are still limitations. Specifically, these research works have focused primarily on one single brain disorder, i.e., sleep disorders or dementia or epilepsy. Additionally, existing research initiatives mentioning some tools, focus mainly on one single type of data, i.e., electroencephalography (EEG) signals or actigraphies or Magnetic Resonance Imaging, and so on. To tackle the aforementioned limitations, this is the first study conducting a comprehensive literature review of the available methods used for supporting the diagnosis of multiple complex brain disorders, i.e., Alzheimer's dementia, sleep disorders, epilepsy. Also, to the best of our knowledge, we present the first study conducting a comprehensive literature review of all the available tools, which can be exploited for processing multiple types of data, including EEG, actigraphies, and MRIs, and receiving valuable forms of information which can be used for differentiating people in a healthy control group and patients suffering from complex brain disorders. Additionally, the present study highlights both the benefits and limitations of the existing available tools.

Electrophysiological variability during tests of executive functioning: A comparison of athletes with and without concussion and sedentary control participants

OBJECTIVE

Sport participation may benefit executive functioning (EF), but EF can also be adversely affected by concussion, which can occur during sport participation. Neural variability is an emerging proxy of brain health that indexes the brain's range of possible responses to incoming stimuli (i.e., dynamic range) and interconnectedness, but has yet to be characterized following concussion among athletes. This study examined whether neural variability was enhanced by athletic participation and attenuated by concussion.

METHOD

Seventy-seven participants (18-25 years-old) were classified as sedentary controls (n = 33), athletes with positive concussion history (n = 21), or athletes without concussion (n = 23). Participants completed tests of attention switching, response inhibition, and updating working memory while undergoing electroencephalography recordings to index neural variability.

RESULTS

Compared to sedentary controls and athletes without concussion, athletes with concussion exhibited a restricted whole-brain dynamic range of neural variability when completing a test of inhibitory control. There were no group differences observed for either the switching or working memory tasks.

CONCLUSIONS

A history of concussion was related to reduced dynamic range of neural activity during a task of response inhibition in young adult athletes. Neural variability may have value for evaluating brain health following concussion.

Dynamic cognitive inhibition in the context of frustration: Increasing racial representation of adolescent athletes using mobile community-engaged EEG methods

Introduction

Concussive events and other brain injuries are known to reduce cognitive inhibition, a key aspect of cognition that supports ones' behaviors and impacts regulation of mood or affect. Our primary objective is to investigate how induction of negative affect (such as frustration) impacts cognitive inhibition and the dynamic process by which youth athletes modulate responses. Secondary objective is to address the lack of Black representation in the scientific literature that promotes brain health and investigates pediatric sports-related brain injury. In particular, neuroscience studies predominantly include White participants despite broad racial representation in sport, in part due to technological hurdles and other obstacles that challenge research access for Black participants.

Methods

Using electroencephalography (EEG), we evaluate the dynamic brain processes associated with cognitive inhibition in the context of frustration induction in adolescent athletes during pre-season conditioning (i.e., prior to contact; N = 23) and a subset during post-season (n = 17).

Results

The N2 component was sensitive to frustration induction (decreased N2 amplitude, slower N2 latency), although effects were less robust at postseason. Trial-by-trial changes indicated a steady decrease of the N2 amplitude during the frustration block during the preseason visit, suggesting that affective interference had a dynamic effect on cognitive inhibition. Lastly, exploratory analyses provide preliminary evidence that frustration induction was less effective for athletes with a previous history of concussion or migraines (trending result) yet more effective for athletes endorsing a history with mental health disorders.

Discussion

We emphasize the urgent need to improve representation in cognitive neuroscience, particularly as it pertains to brain health. Importantly, we provide detailed guides to our methodological framework and practical suggestions to improve representative participation in studies utilizing high-density mobile EEG.

Biofidelic dynamic compression of human cortical spheroids reproduces neurotrauma phenotypes

Fundamental questions about patient heterogeneity and human-specific pathophysiology currently obstruct progress towards a therapy for traumatic brain injury (TBI). Human in vitro models have the potential to address these questions. 3D spheroidal cell culture protocols for human-origin neural cells have several important advantages over their 2D monolayer counterparts. Three dimensional spheroidal cultures may mature more quickly, develop more biofidelic electrophysiological activity and/or reproduce some aspects of brain architecture. Here, we present the first human in vitro model of non-penetrating TBI employing 3D spheroidal cultures. We used a custom-built device to traumatize these spheroids in a quantifiable, repeatable and biofidelic manner and correlated the heterogeneous, mechanical strain field with the injury phenotype. Trauma reduced cell viability, mitochondrial membrane potential and spontaneous, synchronous, electrophysiological activity in the spheroids. Electrophysiological deficits emerged at lower injury severities than changes in cell viability. Also, traumatized spheroids secreted lactate dehydrogenase, a marker of cell damage, and neurofilament light chain, a promising clinical biomarker of neurotrauma. These results demonstrate that 3D human in vitro models can reproduce important phenotypes of neurotrauma in vitro.

Brain Vital Signs in Elite Ice Hockey: Towards Characterizing Objective and Specific Neurophysiological Reference Values for Concussion Management

Background: Prior concussion studies have shown that objective neurophysiological measures are sensitive to detecting concussive and subconcussive impairments in youth ice-hockey. These studies monitored brain vital signs at rink-side using a within-subjects design to demonstrate significant changes from pre-season baseline scans. However, practical clinical implementation must overcome inherent challenges related to any dependence on a baseline. This requires establishing the start of normative reference data sets.

Methods: The current study collected specific reference data for N = 58 elite, youth, male ice-hockey players and compared these with a general reference dataset from N = 135 of males and females across the lifespan. The elite hockey players were recruited to a select training camp through CAA Hockey, a management agency for players drafted to leagues such as the National Hockey League (NHL). The statistical analysis included a test-retest comparison to establish reliability, and a multivariate analysis of covariance to evaluate differences in brain vital signs between groups with age as a covariate.

Findings: Test-retest assessments for brain vital signs evoked potentials showed moderate-to-good reliability (Cronbach’s Alpha > 0.7, Intraclass correlation coefficient > 0.5) in five out of six measures. The multivariate analysis of covariance showed no overall effect for group (p = 0.105), and a significant effect of age as a covariate was observed (p < 0.001). Adjusting for the effect of age, a significant difference was observed in the measure of N100 latency (p = 0.022) between elite hockey players and the heterogeneous control group.

Interpretation: The findings support the concept that normative physiological data can be used in brain vital signs evaluation in athletes, and should additionally be stratified for age, skill level, and experience. These can be combined with general norms and/or individual baseline assessments where appropriate and/or possible. The current results allow for brain vital sign evaluation independent of baseline assessment, therefore enabling objective neurophysiological evaluation of concussion management and cognitive performance optimization in ice-hockey.